Abstract:

Dual referencing has been garnering a lot of attention in the power integrity community, specifically in the voltage mode driver application because it shows a lower overall power delivery noise (PDN) compared to other signal referencing types. Additionally, the increasing push to drive down package and board manufacturing costs is another essential factor to consider dual referencing. As bus operating frequency increases, PDN increases, which could lead to more coupling onto signal nets which, in turn, can distort data and degrade signal integrity. It is generally understood that since dual referenced signals are closer to the power rails, they are more prone to coupling of power delivery noise. As system speeds begin to surpass the 5GT/s range, the noise from the power rails can no longer be neglected. This work provides a comprehensive study of PDN coupling onto signal nets in dual referencing and attempts to quantify the magnitude of the coupling and the factors that increase these noise effects. A dual referenced board was manufactured in order to conduct various experiments to which parameters could be manipulated in order to minimize the effects of the noise. Guidelines to mitigate the effects of PDN in dual referenced boards are proposed.